BATS and rodents, more commonly called rats, mouse or mice, are “unwelcomed” guests in the city.
In the wild, threatened by extinction—mainly because of massive destruction of their habitats—these unique and diverse species perform important ecosystem functions.
While bats are often wrongly associated or linked to the blood-sucking vampire—a mythical creature that feeds by sucking blood from humans and transforms into a bat—these nocturnal flying mammals and night travelers are harmless creatures and are actually beneficial to humans.
Fruit bats are seed-dispersal agents who help keep forests thickly covered with trees naturally, while smaller bats that feed on a variety of insects are nature’s pest-control agents that prevents mosquitoes from spreading the deadly dengue, malaria or Zika virus.
On the other hand, while many consider rats as pest, these small mammals are part of the food chain, and one way or the other, their existence help ensure ecological balance. Biodiversity experts were quick to add that nonnative rats that invade homes and farms are to blame for bats’ bad image.
The native rats live in the wild and continue to provide valuable services, in some cases, in farms by protecting crops against other pests.
Beneficial rats
Some rats eat bugs, including cockroaches and even earthworms. Worm-eating rats, or mice, that feed on giant earthworms were among the discovery of the team that studied the mammals of Luzon.
With a total area of 109,965 square kilometers, Luzon island is the largest of three major island groups comprising the Philippine archipelago. More than half of the country’s population live in Luzon, which puts more human pressure that threaten the extinction of the diverse ecosystem and wildlife found within forests.
Luzon’s remaining forest covers, however, continue to dwindle because of various destructive human activities, like logging, mining and quarrying.
Aggravating the threats to Luzon’s biodiversity is the rampant hunting for food, trophy and sports, and illegal wildlife trade.
Despite urbanization and persistent threat to the integrity of the forest, Luzon has the most number of site-endemic species of mammals in the world, including bats and rats lurking on mountaintops.
In the book The Mammals of Luzon Island—Biogeography and Natural History of a Philippine Fauna, a team of scientists, led by Dr. Lawrence R. Heaney, Danilo S. Balete and Eric A. Richart, concluded that Luzon island now has the highest concentration of unique species of mammals in the world.
Heaney is the Negaunee Curator of Mammals at The Field Museum in Chicago. Balete is a research associate at the Field Museum based in the Philippines, while Richart is a team member who is based at the Natural History Museum of Utah.
Published by The Johns Hopkins University Press and released in April 2016 in the United States, the book is a product of more than 35 years of extensive research on Philippine mammals, with the last 16 years focused on Luzon island.
From 28 species of nonflying small mammals known in Luzon when the research started, the number was doubled to 56 species at the end of 2015, which includes earthworm mice and giant cloud rats.
Of the 56 nonflying or flightless mammals, 52 species of are found nowhere else in the world.
‘Center for evolutionady studies’
Director Theresa Mundita S. Lim of the Biodiversity Management Bureau (BMB) of the Department of Environment and Natural Resources (DENR) said the publication is a testament to the country’s rich biodiversity and endemism.
The findings placed the Philippines, particularly Luzon island, not only as the place with the highest concentration of mammals, but as an important center for evolutionary studies, the understanding of biogeography, and how these should guide conservation actions in the Philippines and elsewhere.
Two new genus: Soricomys and Musseromys
In the course of their 12-year field work and three years of data analysis before coming up with the book, the team concluded that they have discovered two new genus—Soricomys and Musseromys. The two genus are the latest important discovery in the last 50 years.
Genus is a principal taxonomic category that ranks above species and below family, and their discovery has a higher level of significance, Balete said.
Musseromys are tree mice that live on trees and survive on seeds of hard woods. Soricomys, which look like shrews because of their narrow snout, feed on giant earthworms.
Balete said Soricomys can help control the population of giant earthworms that live on the ground. Uncontrolled, earthworms could loosen soil, making them prone to landslide.
“In the Cordillera, for instance, the earthworm-eating mice can help prevent the destruction of our rice terraces,” Balete said, referring to the Banaue Rice Terraces, a United Nations, Educational, Scientific and Cultural Organization World Heritage Site.
One of the first species of Musseromys, the Musseromys gulantang or the Banahao tree-mouse, was discovered on Mount Banahaw in 2004. Three other Musseromys were discovered in Sierra Madre, called Musseromys anacuao; Mount Pulag, the Musseromys benefices, and Mount Amuyao in the Mountain Province, the Musseromys inopitanus.
The Soricomys are actually small mice. “It appears that they are widespread on Luzon but they were never-before recorded or identified,” Balete said.
Luzon tops Brazil, Madagascar in mammal concentration
“In 2000, when we started the research, there were only 28 known mammals. After 12 years, we discovered 28 new mammals,” he said.
Balete said on a per-hectare basis, Luzon now has the highest concentration of mammals, topping even Brazil and Madascar.
“While Brazil and Madagascar have the highest number, in terms of density on a per-hectare basis, Luzon alone has higher concentration of mammals and many of these are site-endemic,” he said.
The findings highlight the need to enhance biodiversity-conservation effort by protecting the country’s forests, Balete said.
‘Sky islands’
Luzon’s mountaintops, which the scientists call sky islands, are centers of endemism, Balete said.
They describe sky islands as “little pockets of distinctive habitats” the animals have learned to adapt.
During the research, the team explored and identified at least eight sky islands that need to be protected.
The sky islands, he said, have paved the way for faster evolution of new species. Inhabitants of these sky islands are unique from one mountaintop to another, he said.
“Imagine that we are only talking about mammals. What more about insects? Our findings highlight the Philippines in global biodiversity,” he said.
The authors of the book observed sped-up version of evolution on mountaintops, particularly among rats. Sped-up evolution happens when animals are isolated from the rest of the world, in places where there are few or no predators or competitors, and where they are able to branch out into special adaptations, eventually forming new species. Luzon, being an island, is not only isolated, but is also covered by mountains, the scientists explained. Balete said they developed the concept of sky islands because of the theory that once upon a time, these mountaintops are islands where mammals have adapted millions of years ago.
From an initial three to four sky islands they later identified mountaintops that host unique species that can be found nowhere else, even in nearby lowland forests.
This, he said, underscores the need to revisit the management regimes under the country’s protected area (PA) system, which does not give special focus to sky islands.
A more important highlight of the research, Balete added, is the uniqueness of the ecosystems on mountaintops.
In the mountains of Cordillera, he said, they discovered that 15 species of mammals are site-endemic.
“This means they can only be found on the mountains of Cordillera and nowhere else in Luzon,” he said.
“Zambales also has its own unique species,” he added.
Bat country
The team also concluded that Luzon, which supports 57 species of bats, most of them live in the hot and humid lowlands. These include the golden-crowned flying fox, which is one of the heaviest bats in the world at up to 2.5 pounds.
Another bat, the smaller flat-headed bat, is so tiny that it can roost inside hollow spaces inside bamboo stems.
With at least 57 known species, bats in the Philippines is the most diverse order of mammals of Luzon. The diversity of bats range terms of size, feeding habit and behavior and appearance.
Some of the bats consume fruits, nectar and blossoms, while others feed on large, hard-shelled beetles, small moths and spiders.
Some species of bats roost in caves, while others in hollow trees, in thick vegetation or in open sunlight on the top of large trees.
The findings of Heaney and his team on the biogeography and natural history of Philippine fauna, Lim said, underscores the importance of continuously enhancing management regimes of the country’s PAs.
She agrees with Balete that mountaintops, or sky islands, need to be protected and conserved as they still hold many secrets that need to be discovered, and the need to come up with area-specific measures for conservation purposes.
“The findings mean that every pocket ecosystem is unique and requires specific management regime for the protection of the unique biodiversity that thrives within that area. This means that you cannot forgo one mountaintop or even a portion of the mountain because of the possibility of causing the extinction of these site-endemic mammals,” Lim explained. Lim said the DENR-BMB is considering to revisit management regimes in PAs to integrate the concept of sky islands that are not outside declared PAs.
